Exhibit 99.1 argenx Announces UK MHRA Approval of VYVGART for the Treatment of Generalized Myasthenia Gravis VYVGART is the first neonatal Fc receptor (FcRn) blocker approved in the UK for the treatment of adults living with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) antibody positive 68% of anti-AChR antibody positive gMG patients treated with VYVGART were responders (n=44/65) on the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale compared with 30% of patient ...